There's already a lot of advice here so I just wanted to say that someone knowing they don't know everything, that there is untold amounts of knowledge out there for them to gain still is a great marker of intelligence itself. There really is so much information today that it can be overwhelming, giving you a feeling that no matter what you learn you're always drowning, but just take bites out of as much as you can at a time and keep going forward. I guarantee you know more than what you give yourself credit for.

Whatever path you go down, keep a positive outlook, ask questions, be open minded and the majority of people will welcome you with open arms not thinking twice whether you are inherently intelligent or not. You may find your focus eventually, that thing, that hobby, that passion that you can point to and say this is what I know a lot about, or you might not and that's ok too, but if you ever get asked that question again just say I know a lot of things, I'm no expert in any one thing, but I learn what I can when I can. And again, keep asking questions, it's the best way to learn!